This invention relates to an engine starting assisting device and more particularly to an engine decompression device.
In many engine applications, the operator may be called upon to manually start an internal combustion engine. This may be true whether or not the engine is also provided with an electrical or otherwise operated self-starting mechanism. For example, it is frequently the practice in outboard motors, and particularly those of small displacement, to incorporate a mechanism whereby the engine may be manually started. This is normally done by a rope or recoil starter mechanism that is associated with a flywheel on the upper end of the crankshaft.
However, in order to achieve good engine performance, it is also the practice to use relatively high compression ratios. The use of such high compression ratios, however, gives rise to rather large forces that must be overcome by the operator to effect manual starting. There have been, therefore, proposed types of devices which effectively lower the compression ratio of the engine during this manual starting procedure. Preferably, such devices should be operative so as to be automatic in nature wherein the compression ratio is lowered only long enough so as to facilitate starting and so as to not interfere with the running of the engine once starting has been accomplished.
Therefore, these previously proposed systems have tended to be somewhat complicated and cumbersome in nature. In addition, they may also have the disadvantage of interfering with the normal operation of the engine.
It is, therefore, a principal object of this invention to provide an improved and simplified decompression device for assisting in engine starting.
It is a further object of this invention to provide an improved, automatic starting decompression device that is operative to reduce the compression ratio only long enough so as to facilitate manual starting and without interfering with the continued running of the engine once starting has been accomplished.
From the foregoing description it should also be readily apparent to those skilled in the art that certain engines may, in some applications, require such decompression devices. In other applications for the same basic engine, however, the decompression device need not be required. For example, in making small displacement outboard motors, electric starters may be offered as an option on some displacements. Where an electric starter is incorporated, the decompression device need not be required. However, if an electric starter is not available or not purchased as an option, then the decompression device may be desirable or an acceptable alternative in lieu of electric starting. The previously-proposed systems, however, have been fairly substantially built into the engine design and the optional addition or subtraction of these features has not been available.
It is, therefore, a still further object of this invention to provide an improved decompression device for an engine that can be easily added or deleted from a given engine with a minimum change in parts and configuration.
It is a further object of this invention to provide an improved decompression device for an engine for facilitating starting and wherein the decompression device can be installed without necessitating substantial disassembly of the engine or without involving modification of the basic engine design.
As has been noted, it is desirable to ensure that the decompression device can operate automatically. One way which this can be done, in accordance with the invention, is by utilizing a centrifugal clutch or centrifugal actuator. As a result, when the engine speed is below a certain speed, the decompression may be effected. However, when that speed is exceeded, the decompression is automatically disabled.
The desirability of maintaining versatility in either utilizing or not utilizing a decompression device with a given engine has already been described. Where centrifugal actuating mechanisms are required, however, it may be desirable or necessary to provide lubrication for certain components of the mechanism.
It is, therefore, a still further object of this invention to provide an improved decompression device and lubrication system therefor when the lubrication system will be effective to lubricate the decompression device when it is installed and which need not be separately built into the engine for the specific application incorporating the decompression device.
That is, it is a further object of this invention to provide a basic engine construction embodying a lubrication system wherein the addition of a decompression device can be accomplished and the existing engine construction will effect lubrication of the decompression device without substantial modification.